Acura RSX Performance Upgrade & Mod Guide

From 2002-2006, the Acura RSX and its performance Type-S variant were two of the most fun cars you could buy. Moderately priced and boasting decent performance, Acura powered the RSX and Type-S with various iterations of the Honda K20 motor. Honda/Acura enthusiasts have long praised the K20 engine for being easy to mod and able to reliably handle power. From the factory, Acura rated the standard RSX at 160 horsepower and 142 lb-ft of torque, and put the RSX Type-S at 200-210 horsepower and 142-143 lb-ft of torque.

While the RSX and Type-S perform admirably stock, they really do well with a few mild engine and suspension mods. Especially considering the cars are coming up on two decades of age, a few performance RSX mods are almost necessary to keep pace with more modern cars. Adding bolt-ons to the engine and suspension is a cost-effective way to increase performance while staying reliable on the RSX.

Acura RSX Performance Mods

• Cold Air Intake
• Exhaust Header and Cat-back Exhaust
• ECU Tuning
• Sway Bar
• Forced Induction

Now let’s get into the 5 best mods for your Acura RSX and RSX Type-S. We kept the list to basic bolt-on engine and suspension upgrades to maximize cost-effectiveness. This is by no means an exhaustive RSX mods list, but is a good intro path to starting your K20A/Z build.

Unfortunately, with time the RSX has become less popular, and as a result, there is not nearly the aftermarket community there once was. By 2022, most of the popular and highest-reviewed manufacturers from the heyday of the RSX in the early 2000s, like Comptech, Greddy, and Cybernation Motorsports, are no longer making parts for the car.

Still, there is a decent RSX mods community out there building and racing K20-powered DC5 Integras. Depending on which RSX engine you start with, you can add 20-35 wheel-horsepower with full bolt-ons. While we won’t go over it in depth, swapping on a Type-S intake manifold and cylinder head to a standard RSX is also a very common mod that nets decent gains, too.

1) Cold Air Intake

By far the most popular mod for the Acura RSX and Type-S is a cold air intake. Not only are they relatively cheap, but they provide a decent performance gain on a naturally aspirated engine. There are two kinds of RSX intakes, either short ram or cold air. We 100% recommend the cold air over the short ram.

After installing a cold air intake, you should see gains of 5-15 horsepower and the car will feel more responsive on the throttle. Relocating the filter brings in cooler air, which increases oxygen content and thus horsepower. The tubing is also much less restrictive and optimized for the best flow.

Finally, though it will be minimal, you’ll also see a mild improvement in fuel economy. The colder air allows the engine to work more efficiently, allowing it to make the same power with less fuel. The difference will probably only be 0.5-1.5 MPG difference, but it adds up over time.

Benefits:

• +5-15 horsepower
• Improved throttle responsiveness
• Increased engine noise
• Improved fuel economy

2) Header and Exhaust

After upgrading to a cold air intake, the next step for most RSX builds is to upgrade the header and exhaust. There are two kinds of headers for the RSX, race headers and shorty headers. The race header makes more power than the shorty header, because race headers eliminate the catalytic converters.

Race headers are not street legal in most places because they are catless, making shorty headers many people’s only option. After upgrading the header, the cat-back portion of the exhaust is also ripe for an upgrade.

Header and Exhaust Benefits:

• +15-25 horsepower (race header)
• Increased exhaust flow
• Increased exhaust sound
• Reduced back pressure

Upgrading the header will net between 15-25 horsepower on the K20-powered RSX and Type-S. An upgraded header will have larger diameter piping, which equates to increased exhaust flow, reduced back pressure, and increased exhaust scavenging. Your engine will be able to breathe easier and expel exhaust quicker with upgraded headers.

Getting a larger cat-back exhaust won’t have the same effect on power as the header, but it will definitely increase exhaust volume and improve the tone. Importantly, most race headers will not connect to the stock exhaust, making a new cat-back or adaptor necessary.

3) ECU Tuning

Now that you have upgraded the intake, header, and exhaust, your next step is to look into RSX ECU tuning. The ECU determines basically every function of how the RSX engine operates, including its performance. By upgrading the RSX’s stock ECU tuning, you can add horsepower, torque, improve the power band, and optimize your mods.

The purpose of the upgraded intake and exhaust is to push more air in and then out of your engine at the highest velocity possible. Tuning helps you get the most out of these upgrades by optimizing parameters like ignition timing, cam timing, and air-to-fuel ratios. You can expect a 15-20% increase in performance from your mods after ECU tuning.

4) Upgraded Rear Sway Bar

Now that we have looked at upgrading the engine with some basic bolt-ons, your next concern should be the car’s handling. From the factory, the RSX is known for having a woefully inadequate suspension setup. While a lot of people start with lowering springs or coilovers, we’d suggest first looking at getting a bigger rear sway bar.

The purpose of the sway bar, also known as an anti-roll bar, is to connect the left and right sides of the suspension together. As a car turns, the weight transfers from both wheels to mainly the outside wheel. The purpose of the sway bar is to clamp down on the springs on the inside wheel, keeping the car level and stopping body roll.

The stock sway bar and rubber bushings are barely adequate for the stock power levels, so when you start adding more they are completely overmatched. Switching to a stiffer and stronger sway bar with better bushings will prevent body roll. A larger size will help with overall stability.

5) Forced Induction

For our final recommendation, we’re going with the heavy hitter: forced induction. To be clear, a turbo or supercharger is far from the first mod you will want to do. However, the K20A/Z engines inside the RSX are pretty limited in what you can achieve power-wise with just bolt-ons. There is only so much the K20 motors can do with natural aspiration. If you want decent power, you will need to add some kind of blower.

There is a lot of debate about how much the stock engine can handle, but the consensus is generally that they can support quite a bit of power. There are some supposedly stock K20A/Z motors making over 500 wheel-horsepower with stock internals and a stock block. For us, we’d say 450 horsepower is probably closer to the limit before you will want to add forged pistons, rods, and head studs for reliability.

The RSX is a Good Platform to Modify

While the Acura RSX and RSX Type-S are not performance machines from the factory, a few tasteful engine and suspension bolt-ons can really wake them up and make them perform on par with much newer cars. The K20 engine is one of the best Honda engines ever created, and all three iterations of the RSX respond to bolt-ons.

Whether you are looking for a few extra horsepower to make getting on the interstate and merging a little easier, or you want a full-blown 450-horsepower monster RSX terrorizing the streets, this guide can help you get there. Don’t forget to upgrade the suspension too, or your newly powerful RSX will be hard to handle.

Let us know about your K20-powered RSX experience below!